Fermentation processes are used throughout the world for the manufacture of foods based on milk from a number of different mammalian sources, including domestic as well as wild animals. These processes typically involve adding lactic acid-producing microorganisms, such as bacteria and yeast to milk, which ingest lactose, or milk sugar, and release lactic acid as waste. Depending on fermentation conditions and milk source, different products are obtained.
Traditional uses of fermented mare's milk are believed to have beneficial effects in relief of metabolic and intestinal problems, gut-cleansing effects coupled with repair of intestinal flora, relief from stomach ulcers, and normalization of blood pressure, cholesterol and liver problems. It has been recommended as an aid in cancer treatment, likely due to enhanced nutrition and support of the immune system.
More recently, researchers have utilized fermented equine milk for the treatment of certain human pathologies, such as hepatitis, chronic ulcer and tuberculosis (Nassal and Rembalski, 1980; Solaroli, Pagliarini and Peri, 1993).
Fermentation agents are typically lactic acid bacteria, such as Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, Lactococcus lactis biovar diacetylactis, and L. acidophilus, and yeasts, such as Leuconostoc mesenteroides, subsp. cremoris. Mixtures of bacteria and/or yeast are used for many different products, including Lactobacillus bulgaricus and Streptococcus thermophilus for yoghurt, and a mixture of bacteria and yeasts for kefir and kumis.
Since ancient times, agrarian cultures have utilized milk for nutrition. Due to a lack of preservation methods and modern methods, such as refrigeration, yeast fermentation was typically used to provide a product that could be safely used over a period of time. However, the fermented milk products differed in quality and characteristics depending on the milk source. Production methods were not controlled and depended on naturally occurring yeasts and bacteria already present in the milk.
Even today in the human populations of central Asia and the former Soviet Union, fermented horse milk is mainly used for the manufacture of a lactic-alcoholic beverage containing from 2-5% alcohol, known as Airag or Koumiss. Typically, the fermentation bacteria utilized are lactic acid bacteria, such as Bifidobacterium mongoliense sp., Lactobaccilus heveticus and Lactobacillus kefiranofaciens. Surono and Hosono (2003) disclose a combination of Lactobacillus lactis subsp. Lactis, Lactobacillus delbrueckii subsp. bulgaricus and the yeast Torula spp. for the production of Koumiss.
Commercially produced fermented products for human consumption include cheese, sour cream, yoghurt and similar products in countries throughout the world, which are known as dahi (Pakistan), kefir (Russia), and créme fraiche (France). Differences between these food products arise from the use of milk with different milk fat contents and the fermentation agent. In many cases the bacteria and/or yeast are unknown or are already present in varying degrees in the collected milk. Some products are consistent in quality after controlled manufacture, e.g., sour cream, but have a short shelf life due to continuing action of the bacteria and/or yeast, e.g., créme fraiche, which has a typical shelf life of 10 days at 4° C. while sour cream has a shelf life of 4 weeks. Cheese exhibits a wide variation depending on milk source and milk fat content, which can range for 1 to 75% milk fat.
In addition to human food, animals have been fed different fermented feeds, traditionally produced by yeasts naturally present in grass crops that have been stored under moist conditions. Dairy farms have supplemented animal diets with rumen-specific live yeast, typically Saccharomyces cerevisiae (CNCM 1-1077), to improve subacute rumen acidosis in cows.
Interest has focused recently on animal feed efficiency and the value of fermented animal fodder for improving animal health and development. Fermented liquid feed for pigs was shown to increase weight 3-5% by using lacto-fermented feedstock (J. Animal Science and Biotechnology, 2015, 6-4). Fermented liquid feed can be produced from agricultural foodstock mixed with water, lactic acid bacteria and yeasts. The pH of liquid feed can be reduced so that stomach pH more efficiently inhibits proliferation of pathogens in the animal.
Nutritional benefits of milk alone are well recognized. Although mammalian milk is comparable in different species, equine milk naturally has better nutritional value than bovine milk.
Horse milk is superior to bovine milk in several characteristics, including: (1) more thermostable whey proteins; (2) less sensitivity to thermal processing; (3) lower casein content; (4) characterization as an albuminous milk; (5) ability to transmit in-utero chemosensory information relative to future food and “additive” products; (6) contains cathelicidins that work like natural antibiotics; (7) equal amounts of β-casein and α-casein; (8) contains N-acetylneuraminic acid (sialic acid) with a high concentration of 0-acetylation at position 4; (9) higher concentrations of lactoferrin and lysozyme; and (10) lysozyme is about 10% compared to trace amounts of lysozyme in bovine milk.
Tables 1-4 illustrate some of the differences in composition between horse and bovine milk.
Table 1 shows the differences between mare's milk and bovine milk.
TABLE 1ParameterEquine MilkBovine MilkCrude protein (g/kg)21.432.5True whey protein (g/kg)8.35.7Casein (g/kg)10.725.1NPN × 6.38 (g/kg)2.41.7(non-protein nitrogen)True whey protein (%)38.7917.54Casein (%)50.0077.23NPN × 6.38 (%)11.215.23Total solids (g/kg)110.0Lactose (g/kg)63.748.8Fat (g/kg)12.136.1Ash (g/kg)4.27.6Gross energy (kcal/kg)480.0674.0
Table 2 compares the lipid concentration of mare's milk and bovine milk.
TABLE 2ParameterEquine milkBovine milkFat (g/kg)12.136.1Triglycerides (%)81.197.0Phospholipids (%)5.01.5Unsaponifiable (%)4.51.5Free Fatty Acids (%)9.4TracePalmitic FA (%)23.829.5Oleic FA (%)19.126.3Linoleic FA (%)9.62.9Linolenic FA (%)9.41.1Saturated FA (%)55.868.0Unsaturated FA (%)44.232.0
Table 3 compares the vitamin and mineral content of mare's milk and bovine milk.
TABLE 3ParameterEquine milkBovine milkCalcium (mg/L) 500-1,3001,100Magnesium (mg/L) 40-110100Zinc (mg/L)0.9-6.44Vitamin E (mg/L)0.26-1.130.6Riboflavin (mg/L)0.371.83
Table 4 shows the differences in casein species and micelle size between mare's milk and bovine milk.
TABLE 4ParameterEquine milkBovine milkCasein (g/kg)10.7025.10αs - casein (%)46.6548.46β - casein (%)45.6435.77κ- casein (%)(7.71)12.69Micelles size (nm)255.00182.00